Calendering roll



l, 1970 I I E. COLLQET 3,543,36

CALENDERING ROLL Filed Nov. 29, 1967 mf 52 31.: D F93 T/ 5* V? i l 1 w "4 .fivrawae. Ewe/vars (cu-tr ATMIy y United States Patent O US. Cl. 29-113 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a calendering roll and, more particularly, to a roll for use in the treatment of the surfaces of strip materials, the shape of the surface of the roll being adjustable by means of inflatable resilient cushions arranged internally along its axis of rotation.

BACKGROUND OF THE INVENTION Calendering systems usually include at least one rotating roll which contacts, with a greater or lesser degree of pressure, the material to be treated, the latter being held by a support surface. Usually, such a system comprises two or more rolls arranged to contact one another along generatrices under the effect either of their own weight or of a supplementary force, such a force generally being exerted on the journals of the upper roll. The pressure zones each comprise a narrow strip on either side of the theoretical generatrix of contact between two cylinders. However, under the effect of the opposed pressure exerted by the coacting cylinders, each cylinder is subjected to a bending force directed toward the side opposite to the pressure zone of the cylinder; this bending force has a harmful effect on the distribution of pressure over the contact surface of the cylinder as a whole and makes this distribution irregular. This gives rise to serious difliculties; various means have already been proposed for overcoming these inconveniences.

Thus, use may be made of cylinders which are given a symmetrical convex curvature in advance, but it is very ditficult to predetermine exactly the necessary degree of convex curvature and it is impossible to modify this curvature during working. Alternatively, means may be provided for exerting, outwardly from the interior of the roll, a pressure which is localised in the zone of action of the roll. That is to say, it is limited to the region over which the roll contacts the material to be treated and to the support surface. Such an arrangement may comprise one or more chambers which are inside the roll and between the shaft and the cylinder wall which form the said roll and which are parallel to the shaft; a fiuid distribution system permits an appropriate pressure to be exerted in that longitudinal chamber which is closest to the working generatrix of the cylinder.

These arrangements for overcoming the problems raised by the bending of calender rolls leave much to be desired either because of their insuificiency or because of the mechanical complications which they involve. Thus, when materials in web form are to be passed between the rolls (for example, in the glazing of paper or for rolling plastics) defects frequently appear in the widthwise direction of the web and persist over a very considerable length of the latter. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a calendering roll that enables the difiiculties of the prior art to be overcome in a fairly simple manner without requiring the use of any complicated or costly 3,543,366 Patented Dec. 1, 1970 devices and using only components which are readily available.

Another object of this invention is the provision of a calendering roll which makes it possible for perfectly uniform rolled products to be obtained consistently; for example, in the case of the glazing of paper, the appli cation of the invention leads to the manufacture without any difficulty, of any desired length of web which is quite regularly glazed and which does not show any defect.

A further object of the present invention is the provision of a calendering roll with Which the defects previously mentioned as appearing on the web and persisting over a considerable length thereof can be eliminated during operation.

It is another object of the instant invention to provide a calendering roll such that it is possible to use rolls which apply a lighter pressure and which are, therefore, more easily manageable, have a smaller inertia and involve less risk of Wear.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

SUMMARY OF THE INVENTION In general, the invention relates to an improved roll which can be used for carrying out various operations which involve pressing. It is useful, particularly, in those operations using at least one roll or cylinder which rotates in contact with a support surface; such operations include rolling, calendering, embossing, glazing, coating, printing, drying, and grinding. The invention is also concerned with a new roll which enables the improved process to be carried into effect; the roll, according to the invention, can be used with advantage in various branches of industry, particularly in connection with paper-making, in the working of plastics materials and rubber, in printing, metallurgy, paint manufacture, and the manufacture of foodstuffs. For the sake of simplicity, reference will be made in this specification to rolls for calendering and the invention will be described hereinafter in its application to calendering rolls. However, it is to be understood that the invention covers all other applications of similar rolls or cylinders, for the treatment of material in sheet, strip, or any other form.

The improved calendering or rolling process, according to the invention, using one or more rolls, consists in subjecting all or part of the internal surface of the or at least one of the rolls, which is hollow, to a pressure directed radially from the interior toward the exterior of the roll by resilient means disposed inside the hollow roll, the resilient force of the said means being directed uniformly in each radial plans about an axis parallel to the axis of the roll.

According to one important characteristic of the invention, the said force is adjustable along the length of the roll; in other words, the force is different in different radial planes, that is to say, in different planes perpendicular to the axis of the resilient means and to the axis of the roll. According to one particularly advantageous embodiment, the internal pressure acting on the wall of the roll is strongest in the central region of the roll and weaker at the ends.

The resilient means may turn at the same time as the roll, or remain stationary, while exerting pressure On the internal wall of the roll.

In a modification of the invention, a force tending to bend the shaft of the roll is applied in a direction perpendicular to the rolling plane to the ends of the shaft where they project beyond the ends of the roll. The roll comprises a rotatable cylindrical casing, a rotatable or stationary shaft mounted on the geometrical axis of the casing, and a resilient means between the shaft and the internal wall of the casing provided for the purpose of exerting a predetermined pressure on the said wall, the said means being mounted symmetrically on an axis parallel to the said shaft and being connected to pressureregulating means externally of the roll. The invention can be carried into effect using resilient means whose axis coincides with that of the roll, or else is parallel but is off-center.

According to one particular embodiment of the invention, the resilient means enter directly into contact with the internal wall of the roll; in other embodiments, they are contained in a support cylinder, the external surface of which is capable of pressing on the internal surface of the roll.

One particularly advantageous embodiment is based on the unexpected discovery that it is possible to use a plurality of rimmed wheels fitted with pneumatic tires and mounted on an axle, or on the actual shaft of the roll, these wheels and tires having dimensions such that the tires are able to come into close contact with the internal wall of the roll, or with the internal wall of a support cylinder situated inside the roll.

When the said rimmed wheels are mounted on the shaft of the roll, there are two possibilities: the hubs of the wheels which carry the pneumatic tires may be fixed to the shaft, or they may turn freely thereon. This corresponds to two methods of using the roll: either it may rotate by being driven by the shaft, or it may be mounted for free rotation about a stationary shaft, In the first of these cases, the tightening or loosening of the tires relative to the internal wall of the casing, due to inflation or deflation thereof, can serve for the transmission or driving power from the shaft to the casing.

Means is provided for the inflation of the said tires with a fluid which is generally air but which could be some other gas or possibly a liquid. In particular, these means may be constructed to permit the tires of the individual wheels, or of groups of wheels, to be inflated separately and independently of the other Wheels or wheelgroups during rotation of the roll.

The cylindrical casing of the roll of the invention can be made of any of the usual materials and can be of a thickness which will not require prohibitive pressures to be exerted to correct the flexing elfected according to the invention. In particular, it may be made of metal, such as steel, bronze or aluminum alloy, or of a synthetic plastics material. It is customary to employ rolls which are lined with a material which is resilient or exible to a greater or lesser degree, such as rubber or synthetic plastics material.

In one particular embodiment of the invention, the cylindrical casing of the roll (that is to say, the actual hollow body of the cylinder forming the roll) has longitudinal slots or grooves extending through the thickness of the casing parallel to the generatrices of the cylinder and stopping at a certain distance before each of the ends of the roll. In this way, a high degree of resilience is given to the body of the roll, and this lends itself particularly well to the action of the internal pressure; this pressure may, in certain cases, cause the roll to assume a shape resembling that of a barrel, thus effectively opposing undesirable flexing due to working of the roll. Rolls of this type are preferably covered with an external protective material.

In the constructional form in which the resilient means are contained in a support cylinder, the latter can have an external diameter equal to or smaller than the internal diameter of the roll; it can be fixed or it can turn.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of two rolls, forming part of a calendering machine;

FIG. 2 is a diagrammatic cross-section of, the middle region of one of the rolls shown in FIG. 1, which is constructed according to the invention;

FIG. 3 is a diagrammatic crosssection of an end region of the roll shown in FIG. 2;

FIG. 4 is an axial sectional view of a roll built in accordance with the invention; and

FIG. 5 is a section on the line II of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG. 1 shows diagrammatically a roll 1 constructed in accordance with the principles of the invention, which turns with a main shaft 2 and which calenders material 4 by rolling it against a second cylinder 3. Indicated inside the roll 1 are arrows which represent pressure vectors acting radially from the interior towards the exterior. The lengths of the arrows are proportional to the pressure. These arrows represent the pressure vectors for, by way of example, seven radial planes A, B, C, D, B, C, D. The cross-sectional views of FIGS. 2 and 3 illustrate the principle of the invention according to which the pressure, regardless of whether it is strong or not so strong at any point along the axis of the roll, is uniformly distributed around the periphery of the roll 1 in each radial plane thereof.

The form of the invention, illustrated in FIGS. 1 to 3, uses pressures which are different in the various radial planes. In one particular case, which is not in any way limitative of the invention but which conforms particularly well to practical requirements, the pressure is strongest in the median plate A (the longest arrows shown in FIG. 1 and also shown in FIG. 2) and weakest in the extreme radial planes D and D (the shortest arrows in FIG. 1 and also shown in FIG. 3).

The practical means for achieving these pressures and for making them different are described hereinafter; it is to be noted that while there is a gradual variation of pressure decreasing symmetrically from the plane A towards B, C, D and on the one hand and towards B, C, D' on the other, the absolute values of pressure may be varied, depending on the nature of the work to be carried out by means of the roll 1. It may be desirable to have a strong pressure which is uniform over a fairly wide region on either side of the plane A covering, for example, the region B'-A-B, and smaller pressures covering the regions CD and CD'. The invention is not limited to any particular distribution of the pressures in the radial planes along the length of the roll. For example, it may be convenient to apply the maximum pressure asymmetrically, such as in the region of C, or B, or B, or C.

The roll, as shown in FIGS. 4 and 5, comprises a rotatable casing in the form of the drum I mounted on the shaft 2 which rotates between two support bearings 7a and 7b; if desired, the shaft 2 may be driven by way of a clutch 8. Rimmed wheels 5a, 5b 5n, disposed side-by-side, are rigidly fixed on the shaft by means of hubs 12a, 12b 12n. These wheels are equipped with inflatable, hollow, annular chambers 6a, 6b 6n, are made of resilient material and are inflated and placed under pressure by means of a fluid. The fluid is introduced into each chamber through separate piping 9a, 9b 911 for each chamber; it is thus possible to introduce the fluid separately into each of the chambers and to obtain different pressures in the different chambers, if this is desired. The said piping systems extend inside the shaft 2 and a distributor 10 permits the fluid to be injected, even when the roll is rotating. A stuffing-box or gland system 11 ensures a hermetically-sealed connection between distributor and shaft when the shaft 2 is moving. A special device inside the distributor permits the chambers to be connected to atmosphere or to be brought under pressure.

The inflatable tubes 6a, 6b, etc., can, in this arrangement, serve as clutches between the shaft 2 and the easing 1; when they are sufliciently inflated and thus sufliciently firmly engaged with the internal wall of the casing 1, the latter becomes locked to the shaft. It is only neces sary to relax the pressure, thus allowing deflation of the chambers 6a, 6b, etc., for the shaft 2 to stop driving the drum 1.

In general terms, it is to be understood that, in the arrangement of the present invention, the nature and the thickness of the walls of the cylinder forming the roll and the radial internal pressure can be so adapted that the cylinder can be subjected to resilient deformation under the action of this pressure.

In operation, the cylinder 1 (FIG. 4) which is turning rolls the material 4 against the opposed cylinder 3 which is also turning. When flexing of the cylinder tends to be produced, the necessary pressure is applied to the interior of the chambers 6a, 6b, etc., in order to counteract the effect of such flexing. If defects are still apparent in the strip or web of rolled product, it is frequently very useful to increase the pressure in the chambers of the corresponding region of the roll. It will be obvious that, if desired, both rolls can be constructed according to the invention.

The roll 1 can operate without bending of the shaft; in this case, adjustment is effected by means of the pressure in the chambers so as to produce a distribution which is either symmetrical with respect to the center of the roll, or asymmetrical; it is also possible to operate with bending of the shaft and with all the chambers at the same pressure, or with bending of the shaft and with symmetrical or non-symmetrical variation of the pressure in the chambers.

It will be clear that the invention is not limited to the details of the embodiments described and that these embodiments are capable of numerous modifications which will suggest themselves to persons skilled in the art without thereby departing from the scope of the invention as defined by the appended claims.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A calendering roll, comprising:

(a) a rotatable cylindrical casing,

(b) a shaft mounted at the geometrical axis of the casing, and

(c) resilient means in the form of a series of annular elements are located between the shaft and the easing, the means being capable of exerting a predetermined pressure on the said casing, the said resilient means consisting of a series of rimmed wheels fitted with pneumatic tubes, the centers of the wheels being mounted on the shaft, the periphery of said tubes being spaced from said centers of the wheels, while the interior of each tube communicates with a source of pressure fluid provided externally of the roll.

2. A calendering roll as recited in claim 1, wherein the major axis of the annular elements coincides with the geometric axis of the casing.

3. A calendering roll as recited in claim 1, wherein the minor axis of the annular elements is situated between the shaft and the internal surface of the casing.

4. A calendering roll as recited in claim 1, wherein the source of pressure fluid is a chamber located adjacent one end of the shaft and nonrotatable therewith, and wherein the pneumatic tubes are connected to the chamber by passages extending axially through the shaft.

References Cited UNITED STATES PATENTS 2,583,117 1/1952 Piperoux et al. 24272 2,648,122 8/1953 Hornbostel 29-113 3,098,284 7/1963 -Hornbostel 29113 3,273,817 9/1966 Damiron 24272 3,295,188 1/1967 Saueressig 24272 BILLY J. WILHITE, Primary Examiner US. Cl. X .R, -162 

